Importing+Geometry+into+AGI


 * Abstract:** //At the time of this writing (4/4/2011), AGI accepts most of the objects that can be created in AutoCAD but not all of them. This is a discussion of the types of geometries that AGI is compatible with. In addition, recommendations and guidelines are given for using AGI to conduct daylight analysis.//

__AGI geometry compatibility__
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 * AGI is compatible with:**
 * 3D Face
 * Polyface Mesh
 * Polygon Mesh
 * 3D Solids
 * Regions
 * Bodies
 * Surfaces (Extruded, Revolved, Lofted, Swept, Planar)
 * Meshes

When importing CAD files into AGI, click on the "Advanced Options" tab as seen in the screen shot below. In the "Advanced Import Options" use the "Curve Increment" input to control how smooth curves will be when importing into AGI. Smoother curves (small degree segments) will look better but will take more time to render and calculate.
 * Guidelines on importing curved solids into AGI**



__**Forming geometries for use with an AGI daylighting study**__
To successfuly analyze a space with an AGI daylighting study, the geometries used must be compatible (see above sections) the model must satisfy two requirements.
 * 1) **All daylight transmitting surfaces (windows, skylights etc.) must have a surface normal that faces towards the interior of the building.** (i.e. the daylight will be traveling in the same direction as the surface normal) //A surface normal for a 3D face is dictated by how the face is drawn in AutoCAD. Using the right hand rule, if the plane is drawn in the counterclockwise direction on the screen, the normal will face out of the scree towards you. The surface normal of regions is in the direction of the Z axis when the region was created. The surface normals of 3D solids face outward. This must be considered if using a 3D solid as a daylight transmitting object.//
 * 2) **Surfaces other than daylight transmitting surfaces must not pass from the interior of the building to the exterior of the building.**//For example, a windowsill that is continuous from inside to outside will not read properly; the sill must be composed of two planes, one outside the glass, and one inside the glass.//If a single plane is used for the windowsill, higher (inaccurate) illuminances may be observed.

The second requirement makes modeling mullions and walls with a thickness quite tedious. In many cases, especially schematic phases of a project, it may be best to forego modeling mullions and wall thickness and merely create a large daylight transmitting surface (which can later be broken up into many patches and elements in AGI for more accurate analysis.) The study listed below analyzes the effects of modeling planes, wall thicknesses, mullions and exterior ground surfaces on room illumination shows that the loss of accuracy from excluding certain details may be acceptable, depending on the situation.